The 21-year-old is back at the Riverside Stadium after spending last season on loan with Nottingham Forest (opens in new tab) - who he helped win promotion back to the Premier League via the play-offs.
But Boro boss Chris Wilder accepts that Spence's future probably lies in North London rather than the North East.
Speaking to The Northern Echo, Wilder said (opens in new tab):
"We’re expecting that deal to happen, but if it doesn’t, then he’s our player. From a club point of view, the deal has to be right.
"We’re not trying to stand in the way of anybody. I’ve never done that as a manager, and I’ve had plenty of situations before where opportunities have come along to players.
"Tottenham want him, and we’re prepared for that. But it’s got to be right for us too. It all needs to marry up."
It's been apparent for some time that Antonio Conte would want to upgrade at right wing-back this summer - and the England U21 international could be the man to replace Emerson Royal, who has never fully convinced in that role.
Boro are said to value Spence - who previously spent time in Fulham (opens in new tab)'s academy - at £15m.
Spurs have already been busy on the transfer front this window, bringing in Ivan Perisic, Yves Bissouma and Fraser Forster.
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Tom Hancock started freelancing for FourFourTwo in April 2019 and has also written for The Analyst and When Saturday Comes, among others. He supports Wycombe Wanderers and can also occasionally be found watching Wealdstone. A self-confessed statto, he has been known to watch football with a spreadsheet (or several) open...